1. Field of the Invention
The present invention relates to an airtight sheath, and more particularly to an airtight sheath having openable air intakes for providing impact-resistant protection for an article.
2. Related Art
A traditional wrapping material is generally provided with a soft inner pad, such as foam, on a peripheral side thereof for protecting articles to be wrapped so as to prevent the articles from being damaged or broken by external vibration. However, the soft inner pad is required to be attached to the wrapping material with additional processes to avoid moving or coming off from the wrapping material, but the additional processes of attaching the soft inner pad are not only cumbersome but also costly to assembly.
In view of the above-mentioned drawbacks, an air inflatable structure is designed to resist impact, with air columns filled with air, and is capable of effectively protecting articles from being vibrated. A conventional air inflatable structure is known to have two pocket sheets and two valve sheets disposed in between and attached to the two pocket sheets, wherein a switch valve path and an air intake channel are formed therein. After being inflated with air, the air inflatable structure is inflated where the switch valve path is blocked to prevent air from leaking out. When air is filled in the air intake channel to inflate the air inflatable structure, the two pocket sheets are pulled outwards by inside air, while a switch valve is not pulled outwards in conjunction with the two pocket sheets. As a result, the two valve sheets of the switch valve are still attached together which causes the air intake channel to be closed and thus air is allowed to flow into the air inflatable structure again. Furthermore, because the two valve sheets are separately attached to outer sheets, assembly processes thus become cumbersome. Moreover, because the outer sheets and inner valve sheets are not assembled and manufactured together, mass production efficiency thereof is seriously affected as well as manufacturing cost. In another example of air inflatable structure, two outer films and two inner films are provided to form the structure, wherein the two inner films are formed with multiple heat-resistant materials, heat-sealing dots, and heat-sealing sides at predetermined locations thereof in order to form air inflation channels. After being inflated with air, the two inner films are inflated to attach to respective outer films and pull away air intakes of the air inflation channels so as to form air columns. However, the above-mentioned air inflatable structure has drawbacks as follows: the two inner films must be lower than the two outer films, and when the heat-sealing dots are not formed at exactly correct positions, the two inner films are to be folded inwards whereby blocking the air intakes causing unsuccessful air filling.
Consequently, it is imperative to improve an inflation structure to be capable of being manufactured with simple processes, automatically rapidly opening air intakes for continuously air charging without causing the block of air intake by inner films, preventing air from flowing reversely and leaking out when stopping air charging, and allowing outer films and inner films to be cut and processed together at the same time.